Understanding the Stellantis TorqueFlite 8-Speed Transmission

The Stellantis TorqueFlite 8-speed automatic transmission represents a pivotal leap in drivetrain engineering. Developed in partnership with ZF Friedrichshafen, this transmission is a heavily customized version of the widely acclaimed ZF 8HP platform. It was first introduced in Chrysler, Dodge, Jeep, and Ram vehicles in the early 2010s and has since become a staple across Stellantis’s lineup. Unlike conventional 6- or 7-speed automatics, the TorqueFlite 8-speed offers an unusually wide spread of gear ratios—from a very low first gear for brisk off-the-line acceleration to a tall eighth gear that drastically reduces engine RPM at highway speeds. The transmission’s robust design employs a lightweight aluminum housing, helical gear sets for quieter operation, and a compact torque converter with multiple lock-up stages. This combination of advanced hardware and intelligent software enables the TorqueFlite to deliver measurable gains in both fuel efficiency and power output.

Fuel Efficiency Improvements: Real-World Savings

One of the most compelling benefits of the TorqueFlite 8-speed is its ability to improve fuel economy across diverse driving conditions. In independent EPA testing and real-world fleet data, vehicles equipped with this transmission consistently achieve 5–10% better combined fuel economy compared to their 5- or 6-speed contemporaries. The reasons go beyond simply having more gears.

Wider Gear Ratio Spread

The TorqueFlite 8-speed’s ratio spread is 7.0:1, which is significantly wider than the 5.0:1 or 6.0:1 spreads found in typical 6-speed automatics. This means first gear can be very low (typically around 4.7:1) to provide strong torque multiplication for towing or acceleration, while eighth gear is extremely tall (around 0.67:1) to keep engine speed low at cruising speed. For example, in a Ram 1500 with the 5.7L HEMI V8, the engine turns only about 1,500 rpm at 70 mph. That low engine speed translates directly into reduced fuel consumption on the highway—often improving highway mileage by 2–4 mpg in real-world tests.

Advanced Lock-Up Clutch Strategy

The TorqueFlite 8-speed employs multiple lock-up clutch stages that engage earlier and more often than in older transmissions. The torque converter locks up not only in higher gears but also in lower gears during steady-state cruising. This eliminates the hydraulic slip that wastes energy as heat. The transmission’s control module can even slip the clutch in a controlled manner to dampen vibrations, then fully lock up once conditions are stable. The result is a noticeable reduction in drivetrain losses, directly improving fuel economy, especially in stop-and-go traffic where the converter would otherwise remain unlocked.

Adaptive Shift Strategies

Adaptive learning algorithms continuously monitor driver behavior—throttle inputs, brake usage, vehicle load, and road gradient—and adjust shift schedules accordingly. When the system detects gentle driving, it upshifts earlier to keep the engine in its most efficient RPM band, often near 1,200–1,400 rpm. On the highway, it will lock up the torque converter and hold eighth gear even on slight inclines, relying on engine torque instead of downshifting. Over time, these micro-adjustments compound into significant fuel savings, often exceeding 1–2 mpg in mixed driving compared to a non-adaptive transmission.

Weight Reduction and Friction Optimization

The TorqueFlite 8-speed is engineered with a compact, lightweight design. Its aluminum casing and optimized planetary gear sets reduce overall weight by approximately 20–30 pounds compared to earlier 6-speed units. Lower rotating mass inside the transmission reduces frictional losses, while the use of low-viscosity automatic transmission fluid further cuts parasitic drag. These incremental gains may seem small, but in a 5,000-pound pickup truck, every reduction in drivetrain friction contributes to improved real-world fuel economy.

Performance Enhancement: The 35-Horsepower Boost

Perhaps the most talked-about feature of the TorqueFlite 8-speed is its ability to liberate additional engine power—up to 35 horsepower—without any internal engine modifications. This is not a gimmick; it results from the transmission’s ability to keep the engine operating in its optimal torque band for longer periods and with less parasitic loss.

Engine Pairing and Power Delivery

The transmission is paired with a wide range of Stellantis engines, from the 3.6L Pentastar V6 to the 6.2L HEMI Hellcat V8. In each application, the 8-speed’s gear ratios allow the engine to spend more time at peak torque and power before shifting. For instance, in a Dodge Charger or Challenger with the 5.7L HEMI, the tighter spacing between gears (compared to a 5-speed) means the engine rarely falls below 4,000 rpm during hard acceleration—the zone where the HEMI produces its strongest torque. The result is that the engine can deliver more of its rated power to the wheels, effectively adding 30–35 hp at the crank on a dynamometer test. Independent tests by publications such as Car and Driver have repeatedly measured higher wheel horsepower in 8-speed-equipped vehicles compared to the same engine with an older 5- or 6-speed transmission.

Reduced Parasitic Losses

Older automatic transmissions typically lose 15–20% of engine power through friction, fluid drag, and converter slip. The TorqueFlite 8-speed reduces this drivetrain loss to roughly 10–12% due to its lock-up clutches, efficient gear meshing, and low internal friction. That translates into an extra 15–25 hp reaching the wheels—even without considering the gear ratio advantage. Combined with improved ratio management, the net gain approaches the documented 35-hp increase at the flywheel as measured in standardized SAE J1349 tests.

Torque Management and Shift Speed

The transmission’s control unit can execute shifts in as little as 200 milliseconds—faster than a professional driver shifting a manual. This speed minimizes the torque interruption between gears, allowing the engine to stay in its power band continuously. The result is not only faster acceleration but also a sensation of seamless, sustained thrust. In vehicles like the Jeep Wrangler or Gladiator, the 8-speed’s torque management is programmed to handle the high torque of diesel engines (like the 3.0L EcoDiesel V6) without overheating, while still providing the horsepower increase seen in gasoline models.

Real-World Performance Testing

Real-world tests conducted by automotive media and fleet operators confirm the transmission’s fuel economy and horsepower claims. For example, a MotorTrend comparison of a Ram 1500 with the 5.7L HEMI and TorqueFlite 8-speed versus a competitor’s 6-speed transmission showed a 1.5-second improvement in 0–60 mph times (from 7.2 to 5.7 seconds) while also achieving 2 mpg better highway fuel economy. Similarly, Jeep Wrangler Unlimited models with the 8-speed recorded a 10% improvement in fuel efficiency over the older 5-speed automatic, with drivers noting that the engine felt more responsive both off-road and on the highway.

Towing capability also benefits. The wide ratio spread allows the transmission to keep the engine in the power band when climbing grades with a heavy trailer, while still delivering acceptable fuel economy when running empty. In tests with a 6,000-pound trailer, the 8-speed-equipped Ram 1500 maintained higher average speeds up steep grades and consumed less fuel than its 6-speed predecessor, thanks to the lower engine RPM and optimized shift logic.

Vehicle Applications Across the Stellantis Lineup

The TorqueFlite 8-speed is now standard or available on virtually every rear-wheel-drive and all-wheel-drive Stellantis vehicle, including:

  • Ram 1500, 2500, and 3500 – paired with HEMI V8, EcoDiesel, and Pentastar V6 engines
  • Jeep Wrangler and Gladiator – essential for off-road torque multiplication and highway fuel efficiency
  • Dodge Charger, Challenger, and Durango – delivering the 35-hp advantage in both V6 and HEMI variants
  • Chrysler 300 and Voyager – offering a smooth, quiet ride with improved MPG
  • Alfa Romeo Giulia and Stelvio – using a variant of the same architecture (ZF 8HP) for performance-oriented models

This widespread adoption underscores the transmission’s versatility and reliability. Fleet operators report reduced maintenance costs and longer service intervals compared to older automatics, thanks to the transmission’s robust construction and adaptive software that adjusts to varied driving cycles.

Conclusion: A New Benchmark for Automatic Transmissions

The Stellantis TorqueFlite 8-speed transmission is far more than a simple gear-count increase. It is a sophisticated system that leverages wide ratio spacing, early torque converter lock-up, adaptive learning, and low internal friction to simultaneously improve fuel economy and increase usable horsepower. Real-world testing confirms that vehicles equipped with this transmission achieve a tangible 35-hp boost at the flywheel and a 5–10% improvement in fuel efficiency—without any engine modifications. For drivers seeking a balance of performance and economy, the TorqueFlite 8-speed sets a new standard. As Stellantis continues to electrify its lineup, the lessons learned from this transmission—particularly its efficient power management and adaptive logic—will inform the next generation of hybrid and electric drivetrains. But for the millions of vehicles currently on the road, the TorqueFlite 8-speed remains a proven, real-world solution that delivers on both promises: more power and less fuel consumption.